Ultrasonic clamp coagulator apparatus having improved clamp mechanism

ABSTRACT

An ultrasonic surgical clamp coagulator apparatus is configured to effect cutting, coagulation, and clamping of tissue by cooperation of a clamping mechanism of the apparatus with an associated ultrasonic end-effector. Selective, indexed rotational positioning of the clamping mechanism and end-effector is achieved by the provision of a detent mechanism incorporated into the clamp drive mechanism of the apparatus. An improved clamping mechanism permits the desired clamping force to be applied to tissue positioned against the end-effector in an instrument having a desirably small cross-section.

TECHNICAL FIELD

The present invention relates generally to ultrasonic surgical devices,and more particularly to an ultrasonic surgical clamp coagulatorapparatus for coagulating and/or cutting tissue, including a clampingmechanism particularly configured to permit application of the desiredclamping in an instrument having a relatively small cross-section.

BACKGROUND OF THE INVENTION

Ultrasonic surgical instruments are finding increasingly widespreadapplications in surgical procedures by virtue of the unique performancecharacteristics of such instruments. Depending upon specific instrumentconfigurations and operational parameters, ultrasonic surgicalinstruments can provide substantially simultaneous cutting of tissue andhemostasis by coagulation, desirably minimizing patient trauma. Thecutting action is typically effected by an end-effector at the distalend of the instrument, with the end-effector transmitting ultrasonicenergy to tissue brought into contact therewith. Ultrasonic instrumentsof this nature can be configured for open surgical use, or laparoscopicor endoscopic surgical procedures.

Ultrasonic surgical instruments have been developed that include a clampmechanism to press tissue against the end-effector of the instrument inorder to couple ultrasonic energy to the tissue of a patient. Such anarrangement (sometimes referred to as an ultrasonic transactor) isdisclosed in U.S. Pat. No. 5,322,055, hereby incorporated by reference.

As will be appreciated, effecting the desired coupling of ultrasonicenergy to the tissue of a patient requires that the clamp mechanism ofan ultrasonic instrument be configured to exert sufficient compressionclamping force between the clamp arm and the associated end-effector.While providing suitable clamp mechanisms in relatively large ultrasonicsurgical instruments has been achieved in the past, presently preferredinstruments are relatively thin, and a relatively small cross-section.By way of example, current instruments have a diameter less than about 6mm, thus limiting the "envelope" within which a clamping mechanism mustbe positioned. As will be recognized, the clamping force is a functionof the moment arm which is created about the pivot axis of the clamp armof the clamping mechanism, with the advent of such relatively smallinstruments limiting the available space for creating the desiredmechanical pivoting force. Additionally, it is ordinarily preferred toprovide an end-effector dimensioned as large as possible, within theconfines of the relatively small instrument, since this desirably abatesexcessive heating of the end-effector, and promotes efficient ultrasoniccutting and coagulation.

The present invention is particularly directed to an ultrasonic clampcoagulator apparatus which includes an improved clamping mechanism whichhas been specifically configured to convert longitudinal motion into apivotal clamping motion for creating the desired clamping force in asurgical instrument having a relatively small cross-section.

SUMMARY OF THE INVENTION

An ultrasonic clamp coagulator assembly embodying the principles of thepresent invention is configured to permit selective cutting,coagulation, and clamping of tissue during surgical procedures. In apresently preferred embodiment, an elongated portion of the instrument,which can be configured for endoscopic applications, it is preferablyconfigured to have an outside dimension of less than about 6 mm. Theconstruction includes a clamping mechanism, including a clamp armpivotally mounted at the distal portion of the instrument, which isspecifically configured to create the desired level of compressionclamping force, notwithstanding the relatively small cross-section ofthe elongated portion.

In accordance with the illustrated embodiment, the present ultrasonicclamp coagulator apparatus includes a housing, and an outer tubularsheath having a proximal end joined to the housing. The outer tubularsheath includes distal end positionable for effecting a surgicalprocedure, with the tubular sheath defining a longitudinal axis of theapparatus.

An inner, preferably tubular actuating member is reciprocably positionedwithin the outer tubular sheath. The actuating member reciprocates foroperation of the clamping mechanism of the apparatus.

An ultrasonic waveguide is positioned within the outer tubular memberand the inner tubular actuating member. The waveguide includes anend-effector extending distally of the distal end of the outer tubularsheath, with ultrasonic energy supplied through the waveguide to theend-effector from an associated ultrasonic drive unit providing thedesired cutting and coagulation of tissue.

The clamping mechanism of the apparatus includes a clamp arm pivotallymounted on the distal end of the outer tubular sheath for pivotalmovement with respect to the end-effector. By this arrangement, tissueis clamped between the clamp arm and the end effector, with suchclamping being possible in absence of ultrasonic energy being suppliedto the end-effector, as may be desirable in some instances.

In order to achieve the desired level of clamping force, the clamp armis pivotal about a pivot axis offset from the longitudinal axis of theapparatus. The clamp arm includes an arrangement, spaced from the pivotaxis of the clamp arm in a direction toward the end-effector, whichoperatively interconnects the clamp arm to the actuating member. In thismanner, reciprocable movement of the actuating member pivots the clamparm with respect to the end-effector.

The arrangement for pivotally moving the clamp arm preferably includesat least one lever portion extending integrally from a clamping portionof the clamp arm. While the specific configuration of the lever portioncan be varied while keeping with the principles disclosed herein, it ispresently preferred that the clamp arm include a pair of lever portionsextending from the pivot axis of the clamp arm on respective oppositesides of the end-effector and longitudinal axis of the apparatus. Theclamping force can thus be transmitted to the clamp arm by the two leverportions acting in concert with each other.

Pivotal operative connection of the lever portions of the clamp arm withthe actuating member is effected by the provision of a pair of openingsdefined by the actuating member within which the lever arms arerespectively positioned. In one embodiment of the present invention,each opening has a notch-like configuration, within which the respectiveone of the lever portions extends. In an alternate embodiment, eachopening defines a generally arcuate surface, with each lever portionincluding a circular pin portion respectively positioned in engagementwith one of the arcuate surfaces.

Other features and advantages of the present invention will becomereadily apparent from the following detailed description, theaccompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ultrasonic surgical system includingan ultrasonic clamp coagulator apparatus embodying the principles of thepresent invention;

FIG. 2 is an enlarged, fragmentary perspective view of a clamp mechanismof the clamp coagulator apparatus illustrated in FIG. 1;

FIG. 3 is a side elevational view, partially in cut-away, of the clampcoagulator embodying the principles of the present invention, shown inoperative association with an ultrasonic drive unit of the surgicalsystem shown in FIG. 1;

FIG. 4 is an exploded view of the ultrasonic surgical clamp coagulatorapparatus embodying the principles of the present invention;

FIG. 5 is an enlarged, fragmentary view of the present clamp coagulatorapparatus illustrating a clamp drive mechanism thereof and associateddetent mechanism;

FIG. 6 is a diagrammatic view further illustrating the clamp drivemechanism and detent mechanism of the present clamp coagulatorapparatus;

FIG. 7 is a diagrammatic view of the detent mechanism of the presentinvention; and

FIG. 8 is a perspective view of a clamp mechanism drive collar of thepresent clamp coagulator apparatus.

FIG. 9 is a fragmentary perspective view further illustrating theclamping mechanism shown in FIG. 2;

FIG. 10 is an exploded diagrammatic view of an alternate embodiment ofthe present clamping mechanism; and

FIG. 11 is a cross-sectional diagrammatic view of the clamping mechanismshown in FIG. 10.

DETAILED DESCRIPTION

While the present invention is susceptible of embodiments in variousforms, there is shown in the drawings and will hereinafter be describeda presently preferred embodiment, with the understanding that thepresent disclosure is to be considered as an exemplification of theinvention, and is not intended to limit the invention to the specificembodiment illustrated.

The present invention is particularly directed to an improved ultrasonicsurgical clamp coagulator apparatus which is configured for effectingtissue cutting, coagulation, and/or clamping during surgical procedures.The present apparatus can readily be configured for use in both opensurgical procedures, as well as laparoscopic or endoscopic procedures.Versatile use is facilitated by selective use of ultrasonic energy. Whenultrasonic components of the apparatus are inactive, tissue can bereadily gripped and manipulated, as desired, without tissue cutting ordamage. When the ultrasonic components are activated, the apparatuspermits tissue to be gripped for coupling with the ultrasonic energy toeffect tissue coagulation, with application of increased pressureefficiently effecting tissue cutting and coagulation. If desired,ultrasonic energy can be applied to tissue without use of the clampingmechanism of the apparatus by appropriate manipulation of the ultrasonic"blade" or end-effector of the device.

As will become apparent from the following description, the presentclamp coagulator apparatus is particularly configured for disposable useby virtue of its straightforward construction. As such, it iscontemplated that the apparatus be used in association with anultrasonic drive unit of a surgical system, whereby ultrasonic energyfrom the drive unit provides the desired ultrasonic actuation of thepresent clamp coagulator apparatus. It will be appreciated that a clampcoagulator apparatus embodying the principles of the present inventioncan be configured for non-disposable use, and non-detachably integratedwith an associated ultrasonic drive unit. However, detachable connectionof the present clamp coagulator apparatus with an associated ultrasonicdrive unit is presently preferred for single-patient use of theapparatus.

With reference first to FIGS. 1 and 3, therein is illustrated apresently preferred embodiment of a surgical system, generallydesignated 10, which includes an ultrasonic clamp coagulator apparatusembodying the principles of the present invention. Preferred details ofthe ultrasonic generator and associated ultrasonic drive unit of thesurgical system 10 will first be described, with subsequent detaileddescription of the ultrasonic surgical clamp coagulator apparatus,including a clamp mechanism configured for indexed rotation, embodyingthe principles of the present invention.

The surgical system 10 includes an ultrasonic generator 30 and anassociated ultrasonic surgical instrument. The surgical instrumentincludes an ultrasonic drive unit, designated 50, and an ultrasonicclamp coagulator apparatus 120 embodying the principles of the presentinvention. As will be further described, an ultrasonic transducer of thedrive unit 50, and an ultrasonic waveguide of the clamp coagulator 120,together provide an acoustic assembly of the present surgical system,with the acoustic assembly providing ultrasonic energy for surgicalprocedures when powered by generator 30. It will be noted that in someapplications, the ultrasonic drive unit 50 is referred to as a "handpiece assembly" because the surgical instrument of the surgical systemis configured such that a surgeon grasps and manipulates the ultrasonicdrive unit during various procedures and operations. The clampcoagulator apparatus 120 embodying the principles of the presentinvention preferably includes a scissors-like grip arrangement whichfacilitates positioning and manipulation of the instrument apart frommanipulation of the ultrasonic drive unit 50.

The generator 30 of the surgical system sends an electrical signalthrough a cable 32 at a selected excursion, frequency, and phasedetermined by a control system of the generator 30. As will be furtherdescribed, the signal causes one or more piezoelectric elements of theacoustic assembly of the surgical instrument to expand and contract,thereby converting the electrical energy into mechanical motion. Themechanical motion results in longitudinal waves of ultrasonic energythat propagate through the acoustic assembly in an acoustic standingwave to vibrate the acoustic assembly at a selected frequency andexcursion. An end-effector at the distal end of the waveguide of theacoustic assembly is placed in contact with tissue of the patient totransfer the ultrasonic energy to the tissue. As further describedbelow, a surgical tool, such as, a jaw or clamping mechanism, ispreferably utilized to press the tissue against the end-effector.

As the end-effector couples with the tissue, thermal energy or heat isgenerated as a result of friction, acoustic absorption, and viscouslosses within the tissue. The heat is sufficient to break proteinhydrogen bonds, causing the highly structured protein (i.e., collagenand muscle protein) to denature (i.e., become less organized). As theproteins are denatured, a sticky coagulum forms to seal or coagulatesmall blood vessels. Deep coagulation of larger blood vessels resultswhen the effect is prolonged.

The transfer of the ultrasonic energy to the tissue causes other effectsincluding mechanical tearing, cutting, cavitation, cell disruption, andemulsification. The amount of cutting as well as the degree ofcoagulation obtained varies with the excursion of the end-effector, thefrequency of vibration, the amount of pressure applied by the user, thesharpness of the end-effector, and the coupling between the end-effectorand the tissue.

As illustrated in FIG. 1, the generator 30 includes a control systemintegral with the generator 30, a power switch 34, and a triggeringmechanism 36. The power switch 34 controls the electrical power to thegenerator 30, and when activated by the triggering mechanism 36, thegenerator 30 provides energy to drive the acoustic assembly of thesurgical system 10 at a predetermined frequency and to drive theend-effector at a predetermined excursion level. The generator 30 drivesor excites the acoustic assembly at any suitable resonant frequency ofthe acoustic assembly.

When the generator 30 is activated via the triggering mechanism 36,electrical energy is continuously applied by the generator 30 to atransducer stack or assembly 40 of the acoustic assembly. A phase-lockedloop in the control system of the generator 30 monitors feedback fromthe acoustic assembly. The phase lock loop adjusts the frequency of theelectrical energy sent by the generator 30 to match the resonantfrequency of the selected longitudinal mode of vibration of the acousticassembly including the tissue load. In addition, a second feedback loopin the control system maintains the electrical current supplied to theacoustic assembly at a preselected constant level in order to achievesubstantially constant excursion at the end-effector of the acousticassembly.

The electrical signal supplied to the acoustic assembly will cause thedistal end of the waveguide, i.e., the end-effector, to vibratelongitudinally in the range of, for example, approximately 20 kHz to 250kHz, and preferably in the range of about 54 kHz to 56 kHz, and mostpreferably at about 55.5 kHz. The excursion of the vibrations at theend-effector can be controlled by, for example, controlling theamplitude of the electrical signal applied to the transducer assembly 40of the acoustic assembly by the generator 30.

As noted above, the triggering mechanism 36 of the generator 30 allows auser to activate the generator 30 so that electrical energy may becontinuously supplied to the acoustic assembly. The triggering mechanism36 preferably comprises a foot activating switch that is detachablycoupled or attached to the generator 30 by a cable or cord.Alternatively, the triggering mechanism can be configured as a handswitch incorporated in the ultrasonic drive unit 50 to allow thegenerator 30 to be activated by a user.

The generator 30 also has a power line 38 for insertion in anelectro-surgical unit or conventional electrical outlet. It iscontemplated that the generator 30 can also be powered by a directcurrent (DC) source, such as a battery. The generator 30 can compriseany suitable generator, such as Model No. GENO1, available from EthiconEndo-Surgery, Inc.

Referring to FIGS. 1 and 3, the ultrasonic drive unit 50 of the surgicalinstrument includes a multi-piece housing 52 adapted to isolate theoperator from the vibrations of the acoustic assembly. The drive unithousing 52 can be shaped to be held by a user in a conventional manner,but it is contemplated that the present clamp coagulator 120 principallybe grasped and manipulated by a scissors-like arrangement provided by ahousing of the apparatus, as will be described. While the multi-piecehousing 52 is illustrated, the housing 52 may comprise a single orunitary component.

The housing 52 of the ultrasonic drive unit 50 generally includes aproximal end, a distal end, and a cavity extending longitudinallytherein. The distal end of the housing 52 includes an opening 60configured to allow the acoustic assembly of the surgical system 10 toextend therethrough, and the proximal end of the housing 52 is coupledto the generator 30 by the cable 32.

The cable 32 preferably includes ducts or vents 62 to allow air to beintroduced into the housing 52 of the ultrasonic drive unit 50 to coolthe transducer assembly 40 of the acoustic assembly.

The housing 52 of the ultrasonic drive unit 50 is preferably constructedfrom a durable plastic, such as Ultem®. It is also contemplated that thehousing 52 may alternatively be made from a variety of materialsincluding other plastics i.e. liquid crystal polymer (LCP), nylon, orpolycarbonate!. A suitable ultrasonic drive unit 50 is Model No. HP050,available from Ethicon Endo-Surgery Surgery, Inc.

The acoustic assembly of the surgical instrument generally includes afirst acoustic portion and a second acoustic portion. The first acousticportion is preferably carried by the ultrasonic drive unit 50, and thesecond acoustic portion (in the form of a waveguide and end-effector, aswill be described) is carried by the ultrasonic clamp coagulatorapparatus. The distal end of the first acoustic portion is operativelycoupled to the proximal end of the second acoustic portion preferably bya threaded connection.

As shown in FIG. 3, the first acoustic portion includes the transducerstack or assembly 40 and a mounting device 84, and the second acousticportion includes a transmission component or working member, referred toherein as a waveguide having an end-effector.

The components of the acoustic assembly are preferably acousticallytuned such that the length of each component is an integral number ofone-half wavelengths (nλ/2), where the wavelength λ is the wavelength ofa preselected or operating longitudinal vibration frequency f₀ of theacoustic assembly, and n is any non-negative integer. It is alsocontemplated that the acoustic assembly may incorporate any suitablearrangement of acoustic elements.

The transducer assembly 40 of the acoustic assembly converts theelectrical signal from the generator 30 into mechanical energy thatresults in longitudinal vibratory motion of the end-effector atultrasonic frequencies. When the acoustic assembly is energized, avibratory motion standing wave is generated through the acousticassembly. The excursion of the vibratory motion at any point along theacoustic assembly depends on the location along the acoustic assembly atwhich the vibratory motion is measured. A minimum or zero crossing inthe vibratory motion standing wave is generally referred to as a node(i.e., where motion is usually minimal), and an absolute value maximumor peak in the standing wave is generally referred to as an anti-node.The distance between an anti-node and its nearest node is one-quarterwavelength (λ/4).

As shown in FIG. 3, the transducer assembly 40 of the acoustic assembly,which is also known as a "Langevin stack", generally includes atransduction portion 90, a first resonator 92, and a second resonator94. The transducer assembly is preferably an integral number of one-halfsystem wavelengths (nλ/2) in length. It is to be understood that thepresent invention may be alternatively configured to include atransducer assembly comprising a magnetostrictive, electromagnetic orelectrostatic transducer.

The distal end of the first resonator 92 is connected to the proximalend of transduction section 90, and the proximal end of the secondresonator 94 is connected to the distal end of transduction portion 90.The first and second resonators 92 and 94 are preferably fabricated fromtitanium, aluminum, steel, or any other suitable material, and mostpreferably, the first resonator 92 is fabricated from 303 stainlesssteel and the second resonator 94 is fabricated from 7075-T651 Aluminum.The first and second resonators 92 and 94 have a length determined by anumber of variables, including the length of the transduction section90, the speed of sound of material used in the resonators 92 and 94, andthe desired fundamental frequency f₀ of the transducer assembly 40. Thesecond resonator 94 can be tapered inwardly from its proximal end to itsdistal end to function as a velocity transformer and amplify theultrasonic vibration excursion.

The transduction portion 90 of the transducer assembly 40 preferablycomprises a piezoelectric section of alternating positive electrodes 96and negative electrodes 98, with piezoelectric elements 100 alternatingbetween the electrodes 96 and 98. The piezoelectric elements 100 can befabricated from any suitable material, such as, for example, leadzirconate-titanate, lead meta-niobate, lead titanate, or otherpiezoelectric material. Each of the positive electrodes 96, negativeelectrodes 98, and piezoelectric elements 100 have a bore extendingthrough the center. The positive and negative electrodes 96 and 98 areelectrically coupled to wires 102 and 104, respectfully. The wires 102and 104 transmit the electrical signal from the generator 30 toelectrodes 96 and 98.

As illustrated in FIG. 3, the piezoelectric elements 100 are held incompression between the first and second resonators 92 and 94 by a bolt106. The bolt 106 preferably has a head, a shank, and a threaded distalend. The bolt 106 is inserted from the proximal end of the firstresonator 92 through the bores of the first resonator 92, the electrodes96 and 98, and piezoelectric elements 100. The threaded distal end ofthe bolt 106 is screwed into a threaded bore in the proximal end ofsecond resonator 94. The bolt can be fabricated from steel, titanium,aluminum, or other suitable material and is preferably fabricated fromTi-6Al-4V Titanium, and most preferably from 4037 low alloy steel.

The piezoelectric elements 100 are energized in response to theelectrical signal supplied from the generator 30 to produce an acousticstanding wave in the acoustic assembly. The electrical signal causes anelectromagnetic field across the piezoelectric elements 100, causing thepiezoelectric elements 100 to expand and contract in a continuous manneralong the axis of the voltage gradient, producing high frequencylongitudinal waves of ultrasonic energy. The ultrasonic energy istransmitted through the acoustic assembly to the end-effector.

The mounting device 84 of the acoustic assembly has a proximal end, adistal end, and preferably has a length substantially equal to anintegral number of one-half system wavelengths. The proximal end of themounting device 84 is preferably axially aligned and coupled to thedistal end of the second resonator 94 by an internal threaded connectionnear an anti-node. (For purposes of this disclosure, the term "near" isdefined as "exactly at" or "in close proximity to".) It is alsocontemplated that the mounting device 84 may be attached to the secondresonator 94 by any suitable means, and the second resonator 94 andmounting device 84 may be formed as a single or unitary component.

The mounting device 84 is coupled to the housing 52 of the ultrasonicdrive unit 50 near a node. The mounting device 84 preferably includes anintegral mounting flange 108 disposed around its periphery. The mountingflange 108 is preferably disposed in an annular groove 110 formed in thehousing 52 of the ultrasonic drive unit 50 to couple the mounting device84 to the housing 52. A compliant member or material 112, such as a pairof silicone rubber O-rings attached by stand-offs, may be placed betweenthe annular groove 110 of the housing 52 and the integral flange 108 ofthe mounting device 86 to reduce or prevent ultrasonic vibration frombeing transmitted from the mounting device 84 to the housing 52.

The mounting device 84 is preferably secured in a predetermined axialposition by a plurality of pins 114, preferably four. The pins 114 aredisposed in a longitudinal direction ninety (90) degrees apart from eachother around the outer periphery of the mounting device 84. The pins 114are coupled to the housing 52 of the ultrasonic drive unit 50 and aredisposed through notches in the acoustic mounting flange 108 of themounting device 84. The pins 114 are preferably fabricated fromstainless steel.

The mounting device 84 is preferably configured to amplify theultrasonic vibration excursion that is transmitted through the acousticassembly to the distal end of the end-effector. In one preferredembodiment, the mounting device 84 comprises a solid, tapered horn. Asultrasonic energy is transmitted through the mounting device 84, thevelocity of the acoustic wave transmitted through the mounting device 84is amplified. It is contemplated that the mounting device 84 beconfigured as any suitable shape, such as, for example, a stepped horn,a conical horn, an exponential horn, a unitary gain horn, or the like.

As shown in FIG. 3, the mounting device 84 is preferably acousticallycoupled to the second acoustic portion of the ultrasonic clampcoagulator apparatus 120. The distal end of the mounting device 84 ispreferably coupled to the proximal end of the second acoustic portion byan internal threaded connection near an anti-node, but alternativecoupling arrangements can be employed.

Referring now to FIG. 4, an exploded view of the ultrasonic clampcoagulator apparatus 120 of the surgical system 10 in accordance with apreferred embodiment is illustrated. The proximal end of the ultrasonicclamp coagulator apparatus 120 preferably receives and is fitted to thedistal end of the ultrasonic drive unit 50 by insertion of the driveunit into the housing of the apparatus, as shown in FIG. 3. Theultrasonic clamp coagulator apparatus 120 is preferably attached to andremoved from the ultrasonic drive unit 50 as a unit. The ultrasonicclamp coagulator 120 may be disposed of after a single use.

The ultrasonic clamp coagulator apparatus 120 preferably includes ahandle assembly or a housing 130, preferably comprising mating housingportions 131, 132, and an elongated or endoscopic portion 150. When thepresent apparatus is configured for endoscopic use, the construction canbe dimensioned such that portion 150 has an outside diameter of about5.5 mm. The elongated portion 150 of the ultrasonic clamp coagulatorapparatus 120 extends orthogonally from the apparatus housing 130. Theelongated portion 150 can be selectively rotated with respect to thehousing 130 as further described below. The elongated portion 150preferably includes an outer tubular member or sheath 160, an innertubular actuating member 170, and the second acoustic portion of theacoustic system in the form of a waveguide 180 having an end-effector180'. As will be described, the outer sheath 160, the actuating member170, and the waveguide 180 are preferably joined together for indexedrotation as a unit (together with ultrasonic drive unit 50) relative tohousing 130.

As illustrated in FIG. 4, the proximal end of the waveguide 180 of thesecond acoustic portion is preferably detachably coupled to the mountingdevice 84 of the ultrasonic drive unit 50 near an anti-node as describedabove. The waveguide 180 preferably has a length substantially equal toan integer number of one-half system wavelengths (nλ/2). The waveguide180 is preferably fabricated from a solid core shaft constructed out ofmaterial which propagates ultrasonic energy efficiently, such astitanium alloy (i.e., Ti-6A1-4V) or an aluminum alloy. It iscontemplated that the waveguide 180 can alternatively be fabricated fromany other suitable material.

The waveguide is preferably substantially semi-flexible. It will berecognized that the waveguide can alternatively be substantially rigidor may comprise a flexible wire. The waveguide may be configured toamplify the mechanical vibrations transmitted through the waveguide tothe end-effector as is well known in the art. The waveguide may furtherhave features to control the gain of the longitudinal vibration alongthe waveguide and features to tune the waveguide to the resonantfrequency of the system.

It will be recognized that the waveguide 180 may have any suitablecross-sectional dimension. For example, the waveguide may have asubstantially uniform cross-section or the waveguide may be tapered atvarious sections or may be tapered along its entire length.

As shown in FIG. 4, the waveguide 180 generally has a first section 182,a second section 184, and a third section 186. The first section 182 ofthe waveguide extends distally from the proximal end of the waveguide,and has a substantially continuous cross-section dimension.

The first section 182 preferably includes at least one radial hole oraperture 188 extending diametrically therethrough, substantiallyperpendicular to the axis of the waveguide 180. The aperture 188 ispreferably positioned at a node, but may be otherwise positioned. Itwill be recognized that the aperture 188 may have any suitable depth andmay be any suitable shape. The aperture is configured to receive aconnector pin member which connects the waveguide 180, the tubularactuating member 170, and the tubular outer sheath 160 together forconjoint, indexed rotation relative to apparatus housing 130.

The second section 184 of the waveguide 180 extends distally from thefirst section 182. The second section 184 preferably also has asubstantially continuous cross-section. The diameter of the secondsection 184 is smaller than the diameter of the first section 182 andlarger than the diameter of the third section 186. As ultrasonic energypasses from the first section 182 of the waveguide 180 into the secondsection 184, the narrowing of the second section 184 will result in anincreased amplitude of the ultrasonic energy passing therethrough.

The third section 186 extends distally from the distal end of the secondsection 184. The third section 186 also has a substantially continuouscross-section. The third section 186 may also include small diameterchanges along its length. As ultrasonic energy passes from the secondsection 184 of the waveguide 180 into the third section 186, thenarrowing of the third section 186 will result in an increased amplitudeof the ultrasonic energy passing therethrough.

The third section 186 may have a plurality of grooves or notches (notshown) formed in its outer circumference. The grooves may be located atnodes of the waveguide 180 to act as alignment indicators for theinstallation of a damping sheath (not shown) and stabilizing siliconerings or compliant supports during manufacturing. A seal is preferablyprovided at the distal-most node, nearest the end-effector 180', toabate passage of tissue, blood, and other material in the region betweenthe waveguide and actuating member 170.

The end-effector 180' of the waveguide 180 is preferably integraltherewith and formed as a single unit. The end-effector may alternatelybe connected by a threaded connection, or by a welded joint. The distalend of the end-effector is disposed near an anti-node in order to tunethe acoustic assembly to a preferred resonant frequency f₀ when theacoustic assembly is not loaded by tissue. When the transducer assemblyis energized, the distal end of the end-effector is configured to movelongitudinally in the range of, for example, approximately 10-500microns peak-to-peak, and preferably in the range of about 10 to about100 microns at a predetermined vibrational frequency f₀.

In accordance with the illustrated embodiment, the end-effector 180',sometimes referred to as a blade, is preferably cylindrical forcooperation with the associated clamping mechanism of the present clampcoagulator apparatus. The end-effector may receive suitable surfacetreatment, as is known in the art.

With particular reference to FIGS. 2 and 9, therein is illustrated theclamping mechanism of the present clamp coagulator 120, which isconfigured for cooperative action with the end-effector 180' of thewaveguide 180. The clamping mechanism includes a pivotally movable clamparm 190, which is pivotally connected at the distal end thereof to thedistal end of outer tubular sheath 160. The clamp arm 190 preferablyincludes a clamping portion 191 which extends distally of the pivot axisof the clamp arm for cooperation with end-effector 180'. A clamp pad192, preferably formed from Teflon or other suitable low-frictionmaterial, is mounted on the surface of a clamping portion 191 of theclamp arm for cooperation with the end-effector 180', with pivotalmovement of the clamp arm positioning the clamp pad in substantiallyparallel relationship to, and in contact with, the end-effector 180'. Bythis construction, tissue to be clamped is grasped between the pad 192and the end effector 180'. As illustrated, the pad 192 is preferablyprovided with a sawtooth-like configuration to enhance the gripping oftissue in cooperation with the end-effector 180'.

Pivotal movement of the clamp arm with respect to the end-effector iseffected by the provision of at least one, and preferably a pair oflever portions 193 of the clamp arm 190 at the proximal end thereof. Thelever portions are positioned on respective opposite sides of thewaveguide 180 and end-effector 180', and are in operative engagementwith a drive portion 194 of the reciprocable actuating member 170.Reciprocable movement of the actuating member, relative to the outertubular sheath 160 and the waveguide 180, thereby effects pivotalmovement of the clamp arm relative to the end-effector. The leverportions 193 can be respectively positioned in a pair of openingsdefined by the drive portion 194 (as will be further described), orotherwise suitably mechanically coupled therewith, whereby reciprocablemovement of the actuating member acts through the drive portion 194 andlever portions 193 to pivot the clamp arm.

As illustrated, each of the lever portions 193 is positioned on arespective opposite side of a longitudinal axis defined by the outertubular sheath 160 of the clamp coagulator apparatus, and on arespective opposite sides of end-effector 180'. While the clamp arm 190is provided with at least one of the lever portions, it is preferredthat a pair of the lever portions be provided for cooperation togetherto effect clamping motion of the clamp arm in response to proximalreciprocation of the actuating member 170.

In this illustrated embodiment, each of the lever portions 193 includesa gusset, designated 193', which desirably rigidities the connection ofeach lever portion to the clamping portion 191 of the clamp arm.Operative connection of each lever arm to the associated actuatingmember is provided by a pair of notch-like openings 195 defined by thedrive portion 194 of the actuating member. The lever portions 193 arerespectively positioned in the openings 195 (see opening 195 in FIG. 9),thus mechanically coupling the clamp arm 190 to the actuating member byrespective pivotal connection of each lever portion.

By the illustrated configuration, the actuating member 170 acts along aline on the lever portions 193 spaced from the pivot axis of the clamparm 190 in a direction toward end-effector 180'. In this embodiment, thepivotal, operative connection of each lever is offset oppositely of theclamp arm pivot axis with respect to the longitudinal rotational axis ofthe elongated portion 150. Maximization of the moment arm thus createdfacilitates creation of the desired compression clamping force againstend-effector 180' within the confines of an instrument having arelatively small cross-section. In current embodiments, outer tubularsheath 160 can be provided with an outside diameter less than about 6mm, with the illustrated clamping mechanism configured to provideclamping force on the order of 2 pounds.

An alternate embodiment of the present clamping mechanism is illustratedin FIGS. 10 and 11. In this alternate embodiment, a modified clamp arm290 includes a clamping portion 291 preferably having a low-friction pad292 (shown in FIG. 11) mounted thereon. Integral lever portions 293extend from the distal portion of the clamp arm 290, with each leverportion including a generally circular pin 293' at the free end thereof.

In this alternate embodiment, the reciprocable actuating member of theapparatus includes a modified drive portion 294 which defines a pair ofopenings 295 each having a generally arcuate surface. The openings 295respectively receive the pins 293' of the lever portions 293 thuseffecting the desired pivotal movement of the clamp arm with respect tothe outer sheath 160.

As illustrated in FIG. 10, the clamp arm 290 includes a bifurcatedportion defining a pair of laterally spaced apart pivot mounts 297 at aproximal portion thereof for pivotally mounting the clamp arm on acooperating mounting portion of outer sheath 160. Pivotal mounting ofthe clamp arm can be effected by the use of a separate pivot pin 299, asshown, or by the provision of suitable integral pivot pin elementsprovided on either the pivot mounts of the clamp arm, or on the distalear portion of outer sheath 160. It is contemplated that the clamp arm190 of the previously described embodiment may similarly be providedwith a pair of pivot mounts like clamp arm 290, or that eitherembodiment can be configured to include an alternative pivotal mountingstructure, such as a proximal portion positioned in pivotal cooperationwith a bifurcated distal portion of outer sheath 160.

As in the previous embodiment, the axis of the pivotal connectionbetween lever portion 293 and drive portion 294 (shown as axis A_(c) inFIG. 11) is offset from the pivotal axis (shown as A_(p)) of the clamparm in a direction toward end-effector 180'. In distinction from theprevious embodiment, wherein the pivotal connections of the leverportions are offset oppositely of the clamp arm pivot axis with respectto the longitudinal rotational axis of elongated portion 150, thepivotal connection of lever portions 293 (along axis A_(c)) is generallyaligned with the longitudinal axis of the elongated portion. While it isdesirable to maximize the moment arm created in the clamp arm of theclamping mechanism, the pivotal connections of the lever portions can bepositioned on the same side of the longitudinal rotational axis as thepivot axis for the clamp arm.

In both of the illustrated embodiments of the present clampingmechanism, it will be appreciated that the lever portions of the clamparm are positioned on respective opposite sides of the associatedend-effector, with the lever arms spaced from and unconnected with eachother. This permits the size of the end-effector to be desirablymaximized, thereby increasing resistance to flexure during tissueclamping, and desirably abating excessive heating of the end-effector,while achieving the desired tissue cutting and coagulation.Additionally, because the lever portions are unconnected at the side ofthe end-effector opposite the pivot axis of the clamp arm, openingmovement of the clamp arm, away from the end effector, is not limited bycontact of the lever portion with the end-effector.

With particular reference to FIGS. 3, 5, and 6, reciprocable movement ofthe actuating member 170 is effected by the provision of a drive collar,generally designated 200, mounted on the proximal end of the actuatingmember for conjoint rotation. To this end, the drive collar includes apair of diametrically opposed axially extending arms 202 each having adrive lug 204, with the drive lugs being biased by the arms 202 intoengagement with suitable openings 206 defined by the proximal portion oftubular actuating member 170. Rotation of the drive collar 200 togetherwith the actuating member 170 is further effected by the provision of apair of keys 208 (see FIG. 8) diametrically engageable with suitableopenings 210 defined by the proximal end of the actuating member 170. Acircumferential groove 211 on the actuating member 170 receives onO-ring 211' (FIG. 4) for engagement with the inside surface of outersheath 160.

Rotation of the actuating member 170 together with tubular outer sheath160 and inner waveguide 180 is provided by a connector pin 212 extendingthrough these components of the apparatus. As illustrated in FIG. 4, thetubular actuating member 170 defines an elongated slot 214 through whichthe connector pin 212 extends to accommodate reciprocable movement ofthe actuating member relative to the outer tubular sheath and innerwaveguide.

A rotation knob 216 mounted on the outer tubular sheath facilitatesrotational positioning of the elongated portion 150 with respect to thehousing 130 of the clamp coagulator apparatus. Connector pin 212preferably joins knob 216 together with sheath 160, member 170, andwaveguide 180 for rotation as a unit relative to housing 130. In acurrent embodiment, hub portion 216' of the rotation knob acts torotatably mount the outer sheath 160, the actuating member 170, and thewaveguide 180 (as a unit with knob 216), on the housing 130.

The drive collar 200 provides a portion of the clamp drive mechanism ofthe apparatus which effects pivotal movement of the clamp arm 190 byreciprocation of actuating member 170. The clamp drive mechanism furtherincludes a drive yoke 220 which is operatively connected with anoperating lever 222 of the apparatus, with the operating lever thusinterconnected with the reciprocable actuating member 170 via drive yoke220 and drive collar 200. The operating lever 222 is pivotally connectedto the housing 130 of the apparatus (by a pivot mount 223) forcooperation in a scissors-like fashion with a handgrip portion 224 ofthe housing. Movement of lever 222 toward handgrip portion 224translates actuating member 170 proximally, thereby pivoting clamp arm190 toward end-effector 180'.

Operative connection of the drive yoke 220 with the operating lever 222is provided by a spring 226, preferably comprising a compression coilspring. The spring 226 fits within a spring slot 228 defined by thedrive yoke 220, which in turn is positioned between a pair of springretainer flanges 230 of the operating lever 222. The drive yoke 220 ispivotally movable with respect to the spring flanges 230 (about pivotmount 223 of housing 130) in opposition to the compression coil spring,which bears against the surfaces of the spring slots defined by each ofthe spring flanges 230. In this manner, the force which can be appliedto the actuating member 170, by pivotal movement of operating lever 222acting through drive yoke 220 and drive collar 200, is limited by theforce with which spring 226 bears against the spring flanges 230.Application of excessive force results in pivotal displacement of driveyoke 220 relative to the spring flanges 230 of the operating lever 222in opposition to spring 226. In a presently preferred embodiment, spring226 is selected to limit clamping force at clamp arm 190 toapproximately 2 pounds. Stop portions of housing 130 limit the travel ofoperating lever 222 to prevent excessive compression of spring 226.

Indexed rotational positioning of the elongated portion 150 of thepresent clamp coagulator apparatus 120 is provided by the provision of adetent mechanism incorporated into the clamp drive mechanism of theapparatus. Specifically, the drive collar 200 includes a pair of axiallyspaced apart drive flanges 232. A detent-receiving surface is providedbetween the drive flanges 232, and defines a plurality ofcircumferentially spaced teeth 234 which define detent-receivingdepressions generally about the periphery of the drive collar 200. In apresently preferred embodiment, twelve (12) of the teeth 234 areprovided, thereby providing indexed positioning of the elongated portion150 of the apparatus at 30° C. intervals relative to the housing 130 ofthe apparatus.

Indexed rotational movement is further achieved by the provision of atleast one, and preferably a pair, of diametrically opposed detents 236respectively provided on cantilevered yoke arms 238 of drive yoke 220.By this arrangement, the yoke arms 238 are positioned between the driveflanges 232 for engagement with the confronting surfaces thereof, andbias the detents 236 into engagement with the drive collar 200. Indexedrelative rotation is thus achieved, with the detents 236 of the yokearms cooperating with the drive flanges 238 for effecting reciprocationof the actuating member 170. In a presently preferred embodiment, thedrive yoke 220 is formed from suitable polymeric material, with thebiasing force created by the yoke arms acting on the detents thereofcooperating with the radial depressions defined by the drive collar toresist relative rotational torque less than about 5 to 20 inch-ounces.As such, the elongated portion 150 of the clamp coagulator apparatus ismaintained in any of its selected indexed rotational positions, relativeto housing 130, unless a torque is applied (such as by rotation knob216) exceeding this predetermined torque level. A snap-like indexingaction is thus provided.

Rotation of the elongated proportion 150 of the present clamp coagulatorapparatus 120 is preferably effected together with relative rotationalmovement of ultrasonic drive unit 50 with respect to apparatus housing130. In order to join the elongated portion 150 to the ultrasonic driveunit 50 in ultrasonic-transmitting relationship, the proximal portion ofthe outer tubular sheath 160 is preferably provided with a pair ofwrench flats 240 (see FIG. 4). The wrench flats allow torque to beapplied by a suitable torque wrench or the like to thereby permit thewaveguide 180 to be joined to the ultrasonic drive unit 50. Theultrasonic drive unit, as well as the elongated portion 150, are thusrotatable, as a unit, by suitable manipulation of rotation knob 216,relative to housing 130 of the apparatus. The interior of housing 130 isdimensioned to accommodate such relative rotation of the drive unit 50.

Thus, the present surgical clamp coagulator apparatus is configured forhighly efficient and versatile use, with the construction beingsufficiently straight-forward and economical in configuration to permitsingle-patient use. Components of the apparatus can be fabricated frommaterials suited for surgical applications. By virtue of the detentmechanism provided by cooperation of drive collar 200 and drive yoke220, selective angular positioning of the elongated portion 150 of theapparatus, and the associated ultrasonic drive unit 50, is readilyeffected with respect to the housing 130 of the apparatus. Thescissors-like action provided by pivotal operating lever 222 andcooperating handgrip portion 224 facilitates convenient and efficientmanipulation and positioning of the apparatus, and operation of theclamping mechanism at the distal portion of the apparatus whereby tissueis efficiently urged against the end-effector 180'. The detent mechanismresists rotation of the ultrasonic drive unit, and associated cableassembly, with respect to the housing 130 with the resistance torotation readily and conveniently overcome by application of sufficienttorque via rotation knob 216.

From the foregoing, it will be observed that numerous modifications andvariations can be effected without departing from the true spirit andscope of the novel concept of the present invention. It is to beunderstood that no limitation with respect to the specific embodimentillustrated herein is intended or should be inferred. The disclosure isintended to cover, by the appended claims, all such modifications asfall within the scope of the claims.

What is claimed is:
 1. An ultrasonic clamp coagulator apparatuscomprising:a housing; an outer tubular sheath having a proximal endjoined to said housing, and a distal end, said tubular sheath defining alongitudinal axis; an inner actuating member reciprocably positionedwithin said outer tubular sheath; an ultrasonic waveguide positionedwithin said outer tubular sheath and having an end-effector extendingdistally of said distal end of said outer tubular sheath, and a clamparm pivotally mounted on said distal end of said outer tubular sheathfor pivotal movement with respect to said end-effector for clampingtissue between said clamp arm and said end effector, said clamp armbeing pivoted about a pivot axis offset from said longitudinal axis;said clamp arm including connecting means spaced from said pivot axis ina direction toward said end-effector for operatively interconnectingsaid clamp arm to said actuating member so that reciprocable movement ofsaid actuating member pivots said clamp arm.
 2. An ultrasonic clampcoagulator apparatus in accordance with claim 1, whereinsaid connectingmeans of said clamp arm includes a pair of lever portions extending fromsaid pivot axis on respective opposite sides of said longitudinal axis,said actuating member including means pivotally interconnecting eachsaid lever portion with said actuating member.
 3. An ultrasonic clampcoagulator apparatus in accordance with claim 2, whereinsaid pivotalconnecting means comprises a pair of openings defined by said actuatingmember for respectively receiving said lever portions.
 4. An ultrasonicclamp coagulator apparatus in accordance with claim 1, whereinsaidpivotal connecting means is offset oppositely of said pivot axis withrespect to said longitudinal axis.
 5. An ultrasonic clamp coagulatorapparatus in accordance with claim 1, whereinsaid clamp arm includes abifurcated portion defining a pair of laterally spaced apart pivotmounts at a proximal portion thereof for pivotally mounting said clamparm on said outer sheath.
 6. An ultrasonic clamp coagulator apparatuscomprising:an outer tubular sheath having a proximal end rotatablyjoined to said housing, and a distal end, said tubular sheath defining alongitudinal axis about which said outer tubular sheath is rotatable; aninner tubular actuating member reciprocably positioned within said outertubular sheath; an ultrasonic waveguide positioned within said innertubular actuating member and having an end effector extending distallyof said distal end of said outer tubular sheath, and a clamp armpivotally mounted on said distal end of said outer tubular sheath forpivotal movement with respect to said end-effector for clamping tissuebetween said clamp arm and said end effector, said clamp arm beingpivoted about a pivot axis offset from said longitudinal axis; saidclamp arm including a pair of lever portions extending from said pivotaxis on respective opposite sides of said end-effector, each said leverportion being operatively connected to said actuating member so thatreciprocable movement of said actuating member pivots said clamp arm. 7.An ultrasonic clamp coagulator apparatus in accordance with claim 6,whereinsaid clamp arm includes a clamping portion extending distally ofsaid pivot axis, each said lever portion including a gusset forrigidifing connection of each said lever portion to said clampingportion.
 8. An ultrasonic clamp coagulator apparatus in accordance withclaim 6, whereinsaid actuating member includes a drive portion defininga pair of openings within which said lever portions are respectivelypositioned for operatively connecting said lever portions to saidactuating member.
 9. An ultrasonic clamp coagulator apparatus inaccordance with claim 8, whereineach said opening in said actuatingmember defines a generally arcuate surface, each said lever portionincluding a generally circular pin respectively positioned in engagementwith one of said arcuate surfaces.
 10. An ultrasonic clamp coagulatorapparatus in accordance with claim 6, whereinsaid outer tubular sheathhas an outside diameter less than about 6 mm.
 11. An ultrasonic clampcoagulator apparatus in accordance with claim 6, whereinsaid leverportions of said clamp arm are operatively connected to said actuatingmember oppositely of said pivot axis with respect to said longitudinalaxis.